This is all very complicated and referencing body parts that I have never even heard of before. But it sounds like a tendon popped out of its groove or sheath. It may have gotten damaged too. They are saying that "stability" is an issue. I can see that if the tendon is not where it is supposed to be.
The repair surgery that is described sounds like putting the tendon back into the groove where it is supposed to be. In the meantime, the question is how much risk is there for him to play more. They can probably stabilize his ankle (I assume this is his ankle) with a mild brace or something like that. That seems like why there is even consideration that he can play.
The Doctors are likely doing more research into this to make sure there is not risk of a catastrophic injury, like Durant tearing his Achilles. But the more salient question may end up being how well can he play with this thing. Even if they can stabilize this enough that there is limited risk of further injury, how much is this going to impact his play. It doesn't seem like a few more days is going to make much difference, so my guess is they do what they can to "stabilize" it and put him out there to see what he can do. Even gimpy, he may be better than Kornet.